He was arrested shortly after his uncle fled house arrest and sought U.S. help in Beijing

Prominent human rights advocate Chen Guangcheng told CNN on Friday the conviction of his nephew in China was retribution for Chen's escape from house arrest and move to the United States.

The People's Court of Yinan County in Shandong Province on Friday convicted Chen Kegui, the nephew, of "intentional infliction of injury" during a clash with local officials in his home, said Chen Kegui's father, Chen Guangfu. The nephew was sentenced to more than three years in prison.

He was arrested in early May in Linyi, a city in Shandong where much of the family lives, shortly after his uncle escaped more than 18 months of heavily guarded house arrest and fled to Beijing.

The family has maintained that Chen Kegui injured a few officials with a kitchen knife in self-defense, when they broke into his house in the middle of the night and attacked his family. Chen Guangfu told CNN that "the verdict was unfair" and that he feels "really disappointed" about it.

"Kegui was just defending himself," his father said, "and it was them breaking into our house and started beating us and trying to take us away."

Chen Guangcheng, in an interview with CNN's Richard Roth in New York, said authorities in China want to perpetuate fear.

"With regard to Chen Kegui, the way that they have handled his case ... in fact this is just the continuation of my own case," the activist said. "With this sentence, Chen Kegui is being made a scapegoat for my situation. Because before this, they tried many times to provoke me, but I didn't fall for their trick."

Authorities in China promised to guarantee the safety of his family and to open an investigation into "the harms my family and I suffered through illegal treatment for years in Shandong," Chen Guangcheng said.

His arrival in the United States on May 19 -- along with his wife and children -- brought an end to a diplomatic firestorm between Beijing and Washington that erupted after he fled from house arrest in Linyi in late April and hid inside the U.S. Embassy in Beijing for a week.

In a video posted online after his escape, Chen addressed Chinese Premier Wen Jiabao, detailing grotesque abuses -- including repeated beatings -- he said he and his family had suffered at the hands of local authorities during captivity.

In the interview Friday, Chen Guangcheng said China has no choice but to change, but he was skeptical.

"Based on the information I have now, especially in light of Chen Kegui's case, I think the new leadership offers no reason for people to put any faith in them," said the activist, who is studying law at New York University.

Amnesty International called the conviction of Chen Kegui "appalling" and retribution for his uncle's escape.

"Amnesty advocates worked with Chen -- a true hero -- in his fight to win rights for China's poor and women and to demand his freedom when it was denied. Now, we will keep this fight going to demand Chen Kegui's freedom." Suzanne Nossel, executive director, Amnesty International USA, said in a statement.

Nicholas Bequelin, a Hong Kong-based senior Asia researcher for Human Rights Watch, said on his Twitter account that "Chen Kegui's trial failed to meet minimum standards of fair trial under domestic or international standards."

Chen Guangfu said his son has told him that he's "in good shape." He said the family was notified of his son's trial only 15 minutes before it began.

The sudden trial Friday also came as a surprise to Chen Kegui's lawyers, who said they became aware that it was happening only when they received calls about it from the news media, said Ding Xikui, one of the lawyers.

Chen Kegui was instead represented by a lawyer designated by the court, according to an official in the court's research office who gave his name only as Li.

His father gave a slightly different account.

According to him, local authorities had promised the family that it was free to hire lawyers for Chen Kegui. But when the family came up with the lawyers, his father said, the local court turned them down and designated two lawyers, Song Kuiyuan and Wang Haijun, to take over the case.

Chen Guangfu, the activist's older brother, said last month that he hadn't been allowed to see his incarcerated son since his arrest.

"There has never been any fairness in this case -- they ignored the facts and refused to let us appoint lawyers for Kegui in accordance with law," he said then. "The whole thing is their revenge against Guangcheng's escape, so I don't have any hope for a fair trial."